Weird Python error

Question

This error: cancel_agreement() missing 1 required positional argument: 'agreement_id'

appeared while executing this method:

def force_cancel(self):
    api = model_from_ref(self.processor.api)
    api.cancel_agreement(self.subscription_reference)
    # transaction.cancel_subscription()  # runs in the callback

Here is cancel_agreement() method:

def cancel_agreement(self, agreement_id, is_upgrade=False):
    note = _("Upgrading billing plan") if is_upgrade else _("Canceling a service")
    r = self.session.post(self.server + '/v1/payments/billing-agreements/%s/cancel' % agreement_id,
                          data='{"note": "%s"}' % note,
                          headers={'content-type': 'application/json'})
    if r.status_code != requests.codes.ok:
        raise RuntimeError(_("Cannot cancel a billing agreement at PayPal. Please contact support."))

I don't understand why the error happens: It is calling a two-argument function (api and self.subscription_reference) and its definition is also two required arguments (self and agreement_id).

Sadly I can't show the entire code, because my business partner is against releasing it open source.

Answer 1

It should be:

def force_cancel(self):
    klass = model_from_ref(self.processor.api)
    api = klass()
    api.cancel_agreement(self.subscription_reference)